Sunday, 31 March 2013

Part 2 - Martyr DOM

In Part 1 we talked about the strength differences between 1020 DOM and Chrome-Moly, two materials commonly used in the construction of roll cages. We concluded that the differences were not sufficient enough to justify the price alone, but Chrome-Moly still has a chance here.

In this part, we're going to go through some fabrication differences as well as comments from people who have worked with both materials.

Only as strong as your weakest link.

Steel sheets are formed and rolled in highly consistent, standardized conditions. Your welds are not. Generally speaking, the quality of the weld will determine the strength of the frame. Tubes (which are what most racing roll cages are made out of) are great at handling axial forces, but those axial forces must be transferred and redirected at welded joints. You have a ton of forces coming from different directions at a joints, as well as stress from rapid expansion and contraction during welding at joints.

Wednesday, 27 March 2013

Part 1 - Holy Moly

No, Chrome-Moly is not a web browser, nor is it a middle name after a complicated marriage.

Chrome-Moly, or SAE 4130 grade steel, is a type of steel that contains chromium and molybdenum alloying elements. This alloy has a better strength to weight ratio than 1020 DOM steel (which we'll talk about later). For this reason, it's used to create structures where weight is very critical, such as high-end bicycle frames, roll cages for race cars, and fuselages on small aircraft.

Chrome-Moly is one of the possible materials we can be using for our frame, because weight is an issue in the competition. In this series of articles, let's do a basic comparison between Chrome-Moly and the standard 1020 DOM (Drawn over Mandrel) steel. Both chrome-moly and 1020 DOM are typically used in the manufacture of roll cages, which makes them a good starting point for the frame.

Welcome to the University of Waterloo Concrete Toboggan team's official blog! Here you'll see our latest updates as we construct a 300 pound concrete and steel toboggan to compete in the 2014 Great Northern Concrete Toboggan Race, hosted in London, Ontario.

For our first post, here are some of the skilled students we have on board who will be contributing technical knowledge to this blog:

Hi! I'm Billy Eakkachaichanvet, the Business Logistics Lead. My role is to execute the business side of the team, such as managing sponsor relations, budgeting and coordinating marketing elements such as this website. I joined the team in the 2012 year because I found the idea of using my studies in civil engineering (i.e. reinforced concrete) in a competitive application (a race) intriguing.